Transcript Tech Goals Review

Energy Optimization at
Westlake’s Ethylene Unit
by
Michael McCaulley
Westlake Petrochemical
Sulphur, La.
Westlake’s Petrochemical Complex



–
Two Ethylene Units
Three Polyethylene Units
One Styrene Unit
Petro-2
 1 Billion Pounds per year
 Start up November 1997
 Ethane - Propane Feed
 Highly Integrated
 Low Pressure Demethanizer with Methane
Refrigeration Compressor
Refrigeration
DeC3
DeC2
DeC1
C3R
Gasoline
PGC
C2R
Quench
E/P Mix
C2H2
Converter
Recycle
Ethane
MAPD
Converter
C4’s
Distillation
Propylene
C3 Splitter
Ethane
C2 Splitter
Cold
Box
H2 &
Methane
Recycle
Propane
Objectives
 Needed
Quickly before APC / RTOpt
 Zero Capital
 High Profit Items only
 Problem Areas Examined
 No need for Increased Production
Approach
 Westlake
defined Potential
 AspenTech Reviewed and Adjusted
 Contract fitted to Objectives
 Scope
 Area
and Overall Plant Models
 Confirm Fit to Actual Operation
 Case Studies of Possible Changes
 Proposed Changes Reviewed then
Implemented
High Priority Areas
 Cold
Box - Demethanizer
 Ethane - Propane Feed Splitter
 Ethylene Splitter
C3R
Ethane
Product
to Petro-1
Feed
Splitter
Ethane-Propane
Feed
C3R
Quench Water
Propane
Furnace Feed
Refrigeration
Recovery
Vaporizers
Feed Splitter



Overhead Propane Spec Change to 1 mol %
Feed Preheater Increase plus 2.5 mm Btu/hr
Bottoms Ethane Spec Change to 50 mol %
Potential Capital Changes


Propylene to the Reboiler
Recycle Ethane to Petro-1
Refrig.
M R Cm prsr
Al.Exchgr
Exchgr
reflux
Cold
Box
C2R
Refrig.
H2 and
CH4 Off Gas
Demethanizer
C2R
FEED
C3R
Deethanizer Feed
Cold Box - Demethanizer
 Shifted
Cold Box Refrigeration Loads
 Optimized Methane Circulation
 Lowered Methane out Bottom
 Lowered Side Reboiler Duty
 Increased Preheater Duty
Cold Box - Demethanizer Results
 Lowered
Ethylene Losses
 Lowered PGC Discharge Pressure
 Reduce Hydrogen to the Demeth
 Reduced C2 Splitter Methane Vent
 Stabilized Operation
C3R
Methane
Vent
Ethylene
Product
FEED
Ethylene
Splitter \ Fractionator
Green Oil
Wash
C2R
Sd Rblrs
C3R
Ethane
Recycle
Ethylene Splitter
 Decreased
Product Purity
 increased
methane and ethane content
 decreased methane recycle vent
 Decreased
Green Oil Wash Rate
 Minimized Ethylene in Bottoms
 balance
reboiler loads
 optimum ethylene loss identified
 maximized reboiler loads by adjusting
refrigeration
Summary
 Feed
Splitter Savings
 Cold Box - Demethanizer
 Ethylene Splitter
$ 240 K
$ 220 K
$ 80 K
Done quickly, & well with a lot of
documentation. Very profitable
Questions ??